The roads and rivers of north-west Ireland are suddenly lined with mink. Managers at Anderson's Mink Farm in Ardara, Donegal, said today that animal right activists cut and opened many of their cages and fences over the weekend, freeing an estimated 5,000 animals into the wilds. About 28,000 stayed behind.

More than 100 have already been recaptured by hunters using cage traps, while several hundred others have been killed by traffic. Drivers have reported seeing groups of the farm-reared animals standing, dazzled by headlights, in the middle of busy roads.

One of the farm's directors, Connie Anderson, blamed animal rights activists for invading the farm in the early hours of Sunday. "These people are animal liberation terrorists and had no thought for the mink or for the damage that will be done to other wildlife in the area," Anderson said.

Agricultural authorities warned that the surviving minks could destroy local populations of salmon, rabbits and fowl. Animal rights activists in Ireland have denied responsibility – but are praising whoever did it.

"We have nothing to do with it," said Bernie Wright, spokeswoman for Ireland's Alliance for Animal Rights. "However, I commend whoever risked their freedom to do this as these animals have a horrendous life."